Publications by authors named "Renato Rozental"

Article Synopsis
  • The study investigates how the brain, particularly the prefrontal cortex (PFC), recovers after injury and focuses on low-frequency oscillatory activity (LFO) as a key factor in this process.
  • Data were collected from a patient, E.L., who had significant PFC damage due to an accident, and assessments included various clinical and neuropsychological tests to understand the relationship between LFO and cognitive function.
  • Findings revealed that LFO activity varied with movement and brain hemisphere recruitment, suggesting potential targets for neuromodulation to improve executive functions, highlighting differences between E.L. and historical cases like Phineas Gage regarding cognitive impairments.
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Melatonin is a neurohormone associated with sleep and wakefulness and is mainly produced by the pineal gland. Numerous physiological functions of melatonin have been demonstrated including anti-inflammation, suppressing neoplastic growth, circadian and endocrine rhythm regulation, and its potent antioxidant activity as well as its role in regeneration of various tissues including the nervous system, liver, bone, kidney, bladder, skin, and muscle, among others. In this review, we summarize the recent advances related to the multiple protective roles of melatonin receptor agonists, melatonin and N-acetylserotonin (NAS), in brain injury, liver damage, and bone health.

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In membrane physiology, as in other fields, myths or speculations may be repeated so often and so widely that they are perceived as facts. To some extent, this has occurred with regard to gap junctions, hemichannels, pannexin channels and P2X7 (ionotropic receptors), especially concerning the interpretation of the individual role of these channels in hypoxic-ischemic CNS since these channels may be closed by the same pharmacological blockers. Significance of existing controversial data are highlighted and contradictory views from different groups are critically discussed herein.

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Objectives/hypothesis: To examine the relationship between hearing and connexin 43, a dominant gap junctional protein in the central nervous system.

Study Design: Original research.

Methods: Connexin 43 heterozygous mice are used to assess its mutational effect on hearing.

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Spreading depression (SD), a slow diffusion-mediated self-sustained wave of depolarization that severely disrupts neuronal function, has been implicated as a cause of cellular injury in a number of central nervous system pathologies, including blind spots in the retina. Here we show that in the hypoglycemic chicken retina, spontaneous episodes of SD can occur, resulting in irreversible punctate lesions in the macula, the region of highest visual acuity in the central region of the retina. These lesions in turn can act as sites of origin for secondary self-sustained reentrant spiral waves of SD that progressively enlarge the lesions.

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Object: One mechanism that contributes to cerebral vasospasm is the impairment of potassium channels in vascular smooth muscles. Adenosine triphosphate-sensitive potassium channel openers (PCOs) appear to be particularly effective for dilating cerebral arteries in experimental models of subarachnoid hemorrhage (SAH). A mode of safe administration that provides timed release of PCO drugs is still a subject of investigation.

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Maternal epilepsy has a potential for fetal injury, either antiepileptic drug (AED)--induced or as a consequence of seizures per se. The intent of this article is to explore this relationship, discussing similar patterns of malformations seen with AEDs or different disease exposure during pregnancy, and the potential role of gap junctional intercellular communication in abnormal morphogenesis.

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Background And Purpose: We investigated the contribution of gap junctions to brain damage and delayed neuronal death produced by oxygen-glucose deprivation (OGD).

Methods: Histopathology, molecular biology, and electrophysiological and fluorescence cell death assays in slice cultures after OGD and in developing rats after intrauterine hypoxia-ischemia (HI).

Results: OGD persistently increased gap junction coupling and strongly activated the apoptosis marker caspase-3 in slice cultures.

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Our knowledge of astroglia and their physiological and pathophysiological role(s) in the central nervous system (CNS) has grown during the past decade, revealing a complex picture. It is becoming increasingly clear that glia play a significant role in the homeostasis and function of the CNS and that neurons should no longer be considered the only cell type that responds, both rapidly and slowly, to electrochemical activity. We discuss recent advances in the field with an emphasis on the impact of hypoxia and ischemia on astrocytic metabolism and the functional relationship between glucose metabolism and gap junctions in astrocytes.

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During development of the retina, programmed cell death helps to establish the final size and distribution of various cell classes in distinct layers of the tissue. Here we show that dying cells in the developing ganglion and inner nuclear layers are clustered spatially and that gap junction inhibitors decrease the clustering of dying cells. To confirm the role of gap junctions in cell death, we induced targeted cell death via intracellular cytochrome c (Cc) and examined the induced cells and their neighbors for apoptotic morphology or caspase-3 cleavage.

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Connexin-null mice and human genetic gap junction diseases illustrate the important roles that gap junction channels play under normal conditions, and the neuro- and cardioprotective effects of gap junction blocking agents demonstrate that closure of these channels may be beneficial in certain pathological situations. This overview summarizes studies in which gap junction modifying reagents have been characterized, highlighting examples of agents for which selectivity for gap junction subtypes has been demonstrated. In addition, strategies for targeting connexin domains through peptide inhibitors are outlined, which may ultimately provide agents that are not only connexin-selective in their actions, but also affect only a subset of a gap junction channel's gating responses.

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